The brake system is to reduce the speed of the wheels of the bicycles gradually until the bicycles are fully stopped. The brake system is a safety system to ensure that the riders control the bicycles safely. The brake system generally includes two brake pads located on two sides of the wheel rim or at the hub where the brake disk is connected.
For those brake systems with two brake pads on two sides of the rim, there are different types such as cantilever type, C type, V type and hydraulic type brake systems. The cantilever type includes two arms and the two brake cables are connected to the two arms, when braking, the two brake cables pull the arms simultaneously to pivot the arms toward the rim. The C type brake system has a fixed arm and a pivotal arm which is connected to the brake cable. When braking, the brake cable pulls the pivotal arms to stop the rim. The V type brake system is similar to the cantilever type and the difference is that the V type does not have a cable frame. The V type uses a solid and curved tube fixed to the pivot and drives the two arms which are pivoted toward the rim when braking.
The C type brake system is mainly used for the bicycles with narrow tires such as the road bicycles and includes cam type and lever type. The cam type means that the arms are driven by a cam mechanism when braking, and the lever type means that the arms are driven by a link mechanism.
U.S. Pat. No. 7,000,739 discloses a cam assisted wheel brake for a bicycle and comprises two arms mounted on a bolt, which provides a pivot point for the arms and a means for attachment of the brake to the fork of the bicycle. The brake incorporates a cam lever pivotably associated with the first arm and which engages a finger portion of the second arm and which comprising a first portion having a screw passing through a bore, a middle portion having a top edge having a curved edge portion, and a second portion pivotably connected to the first arm by a pin extending therethrough. The invention preferably has a quick release mechanism comprising a lever having a first pin extending therefrom, the pin pivotably engaging a bore in the first arm, and a second pin extending off axis from the first pin and pivotably engaging the second portion of the cam lever.
U.S. Pat. No. 3,628,635 discloses a side-pull bicycle brake mechanism and has major and minor arch members wherein it is required to pull upwards on one end of said major arch member by means of a wire in the case a pair of brake shoes are one-sided from the center, and so constructed that a small tensile force can achieve a big brake effect with easy handling by providing simple force magnifying means between the pulling member of said major arch member and said wire, so that said pair of brake shoes can be always actuated and applied equally to the two sides of bicycle rim.
U.S. Pat. No. 7,422,090 discloses a Caliper brake assembly for engaging a rimmed wheel on a frame of a bicycle. First and second brake arms are provided having brake pads supported on first ends thereof and bores extending therethrough for receiving a bolt for providing a pivot point for the pivotal attachment of the first and second brake arms to the bicycle frame. A spring is associated with the first and second arms to bias their brake pads away from the rimmed wheel. A rocker assembly is included in the caliper brake assembly which includes a rocker arm pivotally appended to a second end of the first brake arm, the rocker assembly having a region for fixedly receiving a control cable and a region for pivotally receiving a link, the link provided for pivotally connecting the rocker arm proximate to a second end of the second brake arm.
The first two references use a cam to contact the fixed arm so as to pivot the movable arm so that the brake pads are in contact with rim to stop the wheel. The third reference includes a link unit between the first and second arms, and the link unit is composed of a swing arm and a swing link. The link unit is connected to the first and second arms to control the operation of the second arm.
The present invention relates to a C-type brake system using a cam mechanism. It is noted that the cam mechanism of the prior references is directly in contact with the fixed arm and when the cam rotates the surface with different curvatures of the cam pivots the movable arm to move the brake pads toward the wheel rim.
However, the direct contact between the cam and the fixed arm will wear the fixed arm which has to be replaced after a period of use. The replacement of the fixed arm almost the work to replace the whole C type brake system. Besides, the contact surface of the cam and the fixed arm requires higher standard of machining and the fixed arm has specific outer contour surface which is different to receive high precise machining steps, this means a higher cost is involved. In addition, the resilient member between the overlapped arms is usually inclined because of the overlapped arms and this affects the resilient member to bounce back. The brake cables located above the cam are respectively and alternatively connected to the arms and not located on the same axis so that the bent brake cables do not provide a good braking action.